(1) Field of the Invention
The invention relates to the fabrication of integrated circuit devices, and more particularly, to a method and system that provides automatic support for classification of outgoing DRAM product. Automatic lot splitting and lot is performed in a Manufacturing Information System (MIS) based on test results.
(2) Description of the Prior Art
For typical DRAM test purposes, as detailed in U.S. Pat. No. 5,831,856 (Lin), a Dynamic Random Access Memory (DRAM) testing apparatus is used that includes a substantially upright support plate on which at least one elongated feeding chute is provided, having a channel co-extensive therewith for receiving and holding therein an IC bar, which contains a number of DRAM devices to be tested. The DRAM devices are moved down along the channel by means of gravity. A shifting mechanism, which is controlled by a control unit, sequentially transfers the DRAM devices from the feeding chute to a testing device, defining a holder for receiving the DRAM device to carry out the test. The tests are conducted by the control unit, the test results are transmitted thereto for classification of the DRAM devices being tested. The tested DRAM devices are then forwarded to a movable member to be conveyed thereby to one of a plurality of out-feeding chutes, which are associated with different classifications of the DRAM devices. The DRAM devices are then moved from the out-feeding chute to an empty IC bar to be collected therein.
U.S. Pat. No. 5,901,153 (Chuang) provides a DRAM classification method, which includes a test and classification apparatus that is controlled by a test and classification control process. The test and classification apparatus includes a programmable logic control (PLC) unit, test devices, a conveyer device, electromagnetic driver devices, a man-machine interface, sensors and an alarm. The PLC is operated in accordance with the test and classification process to control the test devices for performing tests on the DRAM devices supplied by at least two supply rails. The electromagnetic driver devices are then used to move the DRAM devices so tested to the conveyer device, which in turn conveys the DRAM devices to a particular collection position in accordance with the characteristic values obtained in the test, which characteristic values being within a particular class of DRAM device associated with a particular collection position, to achieve conveyance and classification of the DRAM device. The man-machine interface provides a manual control and access to the steps of the test and classification control process of the DRAM device. The sensors and the alarm are to detect the condition of out-of-supply of DRAM devices, and to provide a warning of the out-of-supply condition.
The invention teaches an Automatic Classification Shipping (ACS) system that is applied to DRAM devices. The objective of the ACS system of the invention is to automatically classify DRAM devices for purposes of shipment of these devices. This classification can comprise categories of for instance good devices, devices that are functional for certain applications, and the like. The functionality of the ACS is broken down into three categories, that is the function of Classification of the DRAM devices, the function of splitting of the DRAM devices into sub-groups and the function of Combining lots of DRAM devices.